This is because in PLA, the agile and strong style effects buff moves a lot. For example, if you used an agile move and got to attack twice in a row, it would be OP for them to be of a high base power as you used two attacks. Similarly, a strong style move boosted up to a massive amount of power would need the base moves to have lower power level in order to not be an auto-win button.
Also, some moves were completely revamped for Scarlet/Violet like Ceaseless edge, Hisuian Samurott’s signature move. It was 65 base power and left splinters in the opponent, doing damage over time. Now it is of a higher power and leaves spikes as an entry hazard on the opponent’s side of the field.